x^2 = (y - a) / (y - b)

I tried to use this method but it didn't work:

x^2 = (y - a)(y +b) / (y - b)(y +b)

Multiply through by (y-b):


x^2(y-b) = y-a


gather like terms:


y(x^2-1) = bx^2 -a \\
y = \frac {bx^2-a} {x^2 -1}

Thanks for your help and the fact that this question was answered quite quickly.